In generator applications, including without limitation, manufacturing of semiconductor devices, a common reference signal, also known as a common exciter (CEX) may be used to synchronize two or more generators (e.g., R.F. generators). Typical implementations of the CEX feature include a phase locked loop (PLL) using a voltage-controlled oscillator (VCO) to generate the drive signal, where the center frequency of the VCO coincides with the nominal frequency of the generator, and the phase of the VCO is locked using a phase detector.